The aim of this study was to examine some potential effects of 4-Nonylphenol (4-NP), Bisphenol A (BPA), and mixture of them on common carp, Cyprinus carpio and demonstrate induction of vitellogenin (Vtg) as a biomarker for screening aquatic ecosystems. These compounds with other estrogenic chemicals may be responsible for disrupting effects observed in fish. A total of 100 juvenile carp were treated experimentally with 17β-estradiol (E2), and increasing doses of 4-NP, BPA and also mixture of them. Then the plasma Vtg levels were measured using indirect competitive ELISA. Results showed a significant (P<0.05) increase in Vtg levels of exposed carps with E2, maximum 4-NP, BPA and their mixture. The group treated with E2 showed high induction (490%) with respect to controls. The groups treated with maximum dose of 4-NP and BPA showed also induction of Vtg, whereas the group treated with their mixture (3 mg kg−1 b.w. 4-NP and 0.01 mg kg−1 b.w. BPA) showed the highest induction (2126%). Finally, results showed that mixture of 4-NP and BPA exhibited stronger (synergistic) effects. So that, large scale monitoring of estrogenic effects caused by contamination may be considered as a biomarker in urban and industrial effluents.
